It seems its starts out increasing by 10 + 1. However each year it adds 1 more so for year three for example it would be 121 + 12 instead of 11 for the simple fact it increases +1 every year. So in conclusion for the rest of the trucks per year would increase by 10+ ? depending on which year.
Year 3 +12 =133
Year 4 +13 =146
Year 5 +14 =160
Year 6 +15 =175
Year 7 +16 =191
Year 8 +17 =208
Year 9 +18 =226
And so on. :)
