Please tell me the process of calculating those blank part... confusing....

Thank you

Trend Percentages Sales of automotive products for Ford Motor Company and General Motors Corporation for a five-year period are: Net Sales of Automotive Products (Millions of Dollars) Year 1 Year 2 Year 3 Year 4 Year 5 Ford Motor Company General Motors Corporation 99,106 97312 94,828 103,00s 108,027 Net sales for Pfizer Inc. and Abbott Laboratories for the same five years follow $82,879 $81,844 $72,051 $84,407 $91,568 Net Sales (Millions of Dollars) Year 1 Year 2 Year 3 Year4 Year 5 $5,672 $6,406 $6,950 $7,230 $7,478 Pfizer Inc Abbott Laboratories 5,380 6,159 6,877 7,852 8,408 Required Calculate trend percentages for all four companies, using Year 1 as the base year. Round to one decimal point Net Sales of Automotive Products- Trend Percentages Year 1 Year 2 Year 3 Year 4 Year 5 Ford Motor Company General Motors Corporation