13  Commitments and Contingencies 14  Earnings per Share Rental expense was approximately $4.8 million, $3.9 million and $2.4 million for the years ended December 31, 2013, 2012  and 2011, respectively. A summary of the calculation of basic and diluted earnings per share (EPS) for the years ended December 31, 2013, 2012 and  2011 is as follows: For each of the years ended December 31, 2013, 2012 and 2011, 3.2 million, 3.2 million and 1.2 million stock options were outstanding but were not included in the computation of that year’s diluted EPS because the options’ exercise prices were greater than the average market price of the common shares, therefore making them anti-dilutive under the treasury  stock method. As of December 31, 2013, long-lived assets, net totaled $76.7 million, which includes $71.2 million held in the United  States and $5.5 million held outside the United States. As of December 31, 2012, long-lived assets, net totaled $80.2 million,  which includes $73.9 million held in the United States and $6.3 million held outside the United States. In the ordinary course of business, we may be subject to various legal proceedings and claims, including employment disputes, patent claims, disputes over contract agreements and other commercial disputes. In some cases, claimants seek  damages or other relief, such as royalty payments related to patents, which, if granted, could require significant expenditures.  Although the outcome of any claim or litigation can never be certain, it is our opinion that the outcome of all contingencies of which we are currently aware will not materially affect our business, operations, financial condition or cash flows. We lease office space and equipment under operating leases which expire at various dates through 2018. As of December 31, 2013, future minimum rental payments under non-cancelable operating leases with original maturities of greater than 12 months are approximately as follows: ADTRAN 2013 Annual Report 66 (In thousands, except for per share amounts) 2013 2012 2011 Numerator Net Income $45,794 $47,263 $138,577 Denominator Weighted average number of shares—basic 59,001 63,259 64,145 Effect of dilutive securities:  Stock options 390 488 1,236  Restricted stock and restricted stock units 33 27 35 Weighted average number of shares—diluted 59,424 63,774 65,416 Net income per share—basic $0.78 $0.75 $2.16 Net income per share—diluted $0.77 $0.74 $2.12 (In thousands) 2014 $4,523 2015 3,556 2016 2,506 2017 2,156 Thereafter 686 Total $13,427