backlog applied manufactures systems to meet demand represented by order backlog and customer commitments . backlog consists of : ( 1 ) orders for which written authorizations have been accepted and assigned shipment dates are within the next 12 months , or shipment has occurred but revenue has not been recognized ; and ( 2 ) contractual service revenue and maintenance fees to be earned within the next 12 months . backlog by reportable segment as of october 26 , 2014 and october 27 , 2013 was as follows : 2014 2013 ( in millions , except percentages ) .

1	2014	2013	( in millions except percentages )
2	silicon systems group	$ 1400	48% ( 48 % )	$ 1295	55% ( 55 % )
3	applied global services	775	27% ( 27 % )	591	25% ( 25 % )
4	display	593	20% ( 20 % )	361	15% ( 15 % )
5	energy and environmental solutions	149	5% ( 5 % )	125	5% ( 5 % )
6	total	$ 2917	100% ( 100 % )	$ 2372	100% ( 100 % )

applied 2019s backlog on any particular date is not necessarily indicative of actual sales for any future periods , due to the potential for customer changes in delivery schedules or cancellation of orders . customers may delay delivery of products or cancel orders prior to shipment , subject to possible cancellation penalties . delays in delivery schedules and/or a reduction of backlog during any particular period could have a material adverse effect on applied 2019s business and results of operations . manufacturing , raw materials and supplies applied 2019s manufacturing activities consist primarily of assembly , test and integration of various proprietary and commercial parts , components and subassemblies ( collectively , parts ) that are used to manufacture systems . applied has implemented a distributed manufacturing model under which manufacturing and supply chain activities are conducted in various countries , including the united states , europe , israel , singapore , taiwan , and other countries in asia , and assembly of some systems is completed at customer sites . applied uses numerous vendors , including contract manufacturers , to supply parts and assembly services for the manufacture and support of its products . although applied makes reasonable efforts to assure that parts are available from multiple qualified suppliers , this is not always possible . accordingly , some key parts may be obtained from only a single supplier or a limited group of suppliers . applied seeks to reduce costs and to lower the risks of manufacturing and service interruptions by : ( 1 ) selecting and qualifying alternate suppliers for key parts ; ( 2 ) monitoring the financial condition of key suppliers ; ( 3 ) maintaining appropriate inventories of key parts ; ( 4 ) qualifying new parts on a timely basis ; and ( 5 ) locating certain manufacturing operations in close proximity to suppliers and customers . research , development and engineering applied 2019s long-term growth strategy requires continued development of new products , including products that enable expansion into new markets . the company 2019s significant investment in research , development and engineering ( rd&e ) has generally enabled it to deliver new products and technologies before the emergence of strong demand , thus allowing customers to incorporate these products into their manufacturing plans at an early stage in the technology selection cycle . applied works closely with its global customers to design systems and processes that meet their planned technical and production requirements . product development and engineering organizations are located primarily in the united states , as well as in europe , israel , taiwan , and china . in addition , applied outsources certain rd&e activities , some of which are performed outside the united states , primarily in india and singapore . process support and customer demonstration laboratories are located in the united states , china , taiwan , europe , and israel . applied 2019s investments in rd&e for product development and engineering programs to create or improve products and technologies over the last three years were as follows : $ 1.4 billion ( 16 percent of net sales ) in fiscal 2014 , $ 1.3 billion ( 18 percent of net sales ) in fiscal 2013 , and $ 1.2 billion ( 14 percent of net sales ) in fiscal 2012 . applied has spent an average of 13 percent of net sales in rd&e over the last five years . in addition to rd&e for specific product technologies , applied maintains ongoing programs for automation control systems , materials research , and environmental control that are applicable to its products. .

Previous questions in this conversation: what were net sales in 2014? and in 2013? so how much did this value change between the two years?
Previous answers: 0.0875 0.07222 0.01528
Question: and the percentage change during this time?
Answer: 0.21154