of operation. Our web store and temporary and seasonal locations are  not included in our comparable store calculations. Non-comparable  stores also result from a store relocation or remodel that results in  a significant change in square footage. The net retail sales for that  location are excluded from comparable store sales calculations until  the thirteenth full month of operation after the date of the change.  We have a loyalty program with a frequent shopper reward feature,  the Stuff Fur Stuff ®   club. Members of the program receive one point  for every dollar spent and receive awards after reaching certain point  thresholds. On a quarterly basis, an estimate of the obligation related  to the program, based on actual points, awards outstanding and  historical point conversion and award redemption patterns, is recorded  as an adjustment to the deferred revenue liability and net retail sales.  As the awards can be earned or redeemed at any of our store locations,  we account for changes in the deferred revenue account at the total  company level only. Therefore, when we refer to net retail sales by  location, such as comparable stores or new stores, these amounts do  not include any changes in deferred revenue. See “-Critical Accounting  Estimates” for additional details on the accounting for the deferred  revenue related to our customer loyalty program. We use net retail sales per square foot and comparable store sales as  performance measures for our business. The following table details  net retail sales per square foot for the periods presented: (1)   Net retail sales per gross square foot in North America represents net retail sales  from stores open throughout the entire period in North America divided by the  total gross square footage of such stores.  (2)   Excludes our web store and temporary and seasonal locations.  (3)   Net retail sales per selling square foot in Europe represents net retail sales from  stores open throughout the entire period in Europe divided by the total selling  square footage of such stores. The percentage increase (or decrease) in comparable store sales for  the periods presented below is as follows: (1) Comparable store sales percentage changes are based on net retail sales and stores  are considered comparable beginning in their thirteenth full month of operation.  (2)   Excludes our web store and temporary and seasonal locations.  Fiscal 2013 consolidated comparable store sales for the full year  are compared to the 52 week period ended December 29, 2012. We  attribute the increase in comparable store sales for the periods  presented primarily to the impact of our brand marketing and  product strategies which have improved results in our overall store  base and our real estate optimization strategies which have driven  sales in selective markets impacted by store closures and remodels.  Fiscal 2012 consolidated comparable store sales for the full year are  compared to the 52 week period ended December 31, 2011 We believe  the primary drivers of the overall decline in consolidated comparable  store sales for the full year were as follows:  Franchise fees:  We receive an initial, one-time franchise fee for each  master franchise agreement which is amortized to revenue over the  initial term of the respective franchise agreements, which extend for  2013 FORM 10-K 18  BUILD-A-BEAR WORKSHOP, INC.  Fiscal  2013 Fiscal  2012 Fiscal  2011 Net retail sales per gross square foot - North America  (1) (2) $ 381 $ 350 $  354 Net retail sales per selling square foot - Europe (2) (3) £ 525 £ 511 £ 562 Fiscal  2013 Fiscal  2012 Fiscal  2011 Comparable store sales change - North America (%)  (1) (2) 5.7% (2.0)%  (2.5)% Comparable store sales change - Europe (%)  (1) (2) 2.9% (8.4)% (0.2)% Comparable store sales change - Consolidated (%)  (1) (2) 5.1% (3.3)% (2.1)% • The growth in our base business accounted for approximately 70%  of the overall comparable store sales increases in 2013 which we  believe were driven by:  • A 30% reduction in discounts in North America which  contributed to higher transaction value in 2013; and • Our brand building marketing initiatives, including  national television advertising in the United States, along  with a balance of proprietary and licensed product, which  we believe increased traffic to our stores and contributed to  an increase in transactions.  • We believe that our real estate optimization strategies drove the  remaining 30% of the overall comparable store sales increase in  2013. The real estate optimization plans include selective store  closures, primarily in North American multi-store markets, as well  as updates and remodels of select other stores. These actions drove  a 9% increase in sales per square foot in North America, reversing a  multi-year decline. • In the first half of 2012, we had benefit from higher redemption  rates and transaction value of our holiday gift cards and from a  promotion in the United States with McDonald’s Happy Meals ®  that drove awareness of our brand and brought traffic to our stores  resulting in slightly positive comparable store sales in North  American through the first twenty-six weeks. • In the fiscal 2012 third quarter, we experienced a decline in the  number of transactions compared to the 2011 third quarter which  benefited from a strong product offering that was tied to a major  theatrical release supported by studio marketing and advertising.  • In the fiscal 2012 fourth quarter, we believe our new brand building  marketing campaign in the United States along with a return to  traditional holiday product offerings resulted in an increase in  North American comparable store sales.  • In the United Kingdom, we believe the negative economic  conditions contributed to a continued decline in consumer  sentiment and a corresponding decline in spending that negatively  impacted our comparable store sales throughout the year.