procedures, as well as certain research applications continue to be negatively impacted by COVID-19 but to a lesser extent than in mid-fiscal 2020. We are seeing indications that the market is starting to recover. We anticipate the defense market, especially amplifiers for directed energy, countermeasures as well as specialty optics for aerospace, to be a multi-year growth opportunity for us. The decrease in scientific and government programs market sales of $20.6 million, or 16%, during fiscal 2020 was primarily due to lower demand for advanced research applications used by university and government research groups, primarily in the United States and Asia, due to the closures of universities and research institutions due to COVID-19 shelter-in-place orders during mid-fiscal 2020. We saw improved demand in the fourth quarter of fiscal 2020 as universities and research institutions began to reopen. We expect demand in the scientific and government programs market to continue to fluctuate from quarter to quarter. The timing for shipments of our higher average selling price ELA tools in the flat panel display market has historically fluctuated and is expected to continue to fluctuate from quarter-to-quarter due to customer scheduling, market conditions, our ability to manufacture these products and/or availability of critical component parts and supplies. As a result, the timing to convert orders for these products to net sales will likely fluctuate from quarter-to-quarter. We have historically generally experienced decreased revenue in the first fiscal quarter compared to other quarters in our fiscal year due to the impact of time off and business closures at our facilities and those of many of our customers due to year-end holidays. For example, over the past 10 years, excluding certain recovery years, our first fiscal quarter revenues have ranged 2%-17% below the fourth quarter of the prior fiscal years. In fiscal 2020 and 2019, one customer accounted for 17% of net sales. We are organized into two reportable operating segments: OLS and ILS. While both segments deliver cost-effective, highly reliable photonics solutions, OLS is focused on high performance laser sources and complex optical sub-systems, typically used in microelectronics manufacturing, medical diagnostics and therapeutic applications, as well as in scientific research. ILS delivers high performance laser sources, sub-systems and tools primarily used for industrial laser materials processing, serving important end markets like automotive, machine tools, consumer goods and medical device manufacturing. The following table sets forth, for the periods indicated, the amount of net sales and their relative percentages of total net sales by segment (dollars in thousands): Net sales for fiscal 2020 decreased $201.6 million, or 14%, compared to fiscal 2019, with decreases of $127.7 million, or 14%, in our OLS segment and decreases of $73.9 million, or 14%, in our ILS segment. The fiscal 2020 decreases in both OLS and ILS segment sales included decreases due to the unfavorable impact of foreign exchange rates. The decrease in our OLS segment sales in fiscal 2020 was primarily due to weaker demand for ELA tools resulting in lower shipments of ELA tools used in the flat panel display market and lower revenues from consumable service parts. The decrease included lower sales of approximately $26.0 million due to COVID-19. In addition, the decrease was due to a non-recurring fee of $7.0 million that was recognized in the first quarter of fiscal 2019 related to the cancellation of orders from one customer for our ELA tools. In addition, OLS sales decreased due to lower demand for advanced research applications used by university and government research groups, primarily in the United States and Asia. The decrease in our ILS segment sales from fiscal 2019 to fiscal 2020 was primarily due to lower sales for materials processing and lower sales for medical applications within the OEM components and instrumentation market. The decrease included lower sales of approximately $14.0 million due to COVID-19. 56 Fiscal 2020 Fiscal 2019 Amount Percentage of total net sales Amount Percentage of total net sales OEM Laser Sources (OLS) $ 758,929  61.8  % $ 886,676  62.0  % Industrial Lasers & Systems (ILS) 470,070  38.2  % 543,964  38.0  % Total $ 1,228,999  100.0  % $ 1,430,640  100.0  % Segments