The following items appeared in the Investing Activities section of Apple Inc.'s statement of cash flows included in Form 10-K for the year ended September 26, 2015. (All amounts are in millions of dollars.) 2015 2014 2013 Purchases of marketable securities $(166,402) $(217,128) $(148,489) Proceeds from maturities of marketable securities 14,538 18,810 20,317 Proceeds from sales of marketable securities 107,447 189,301 104,130 Required: 1. What amount did Apple spend in 2015 to purchase marketable securities? million $ How does this amount compare to the amounts spent in the two prior years? This was $ million