How I can explain the different in common size balance sheet between many years in same company? for

How I can explain the different in common size balance sheet between many years in same company?

for example if cash goes up from 4% to 33% AMAZON.COM, INC. COMMON SIZE BALANCE SHEETS AS OF December 31, December 31, December 31, 2018 2008 1998 ASSETS Current Assets:     Cash and Equivalents 19.5% 33.3% 4.0%     Marketable Securities 5.8% 11.5% 53.6%     Inventories 10.6% 16.8% 4.6%     Accounts Receivable and Other 10.3% 12.4% 3.2%       Total Current Assets 46.2% 74.1% 65.5% Net Property and Equipment 38.0% 10.3% 4.6% Goodwill 8.9% 5.3% 28.7% Other Assets 6.9% 10.4% 1.2% Total Assets 100.0% 100.0% 100.0% LIABILITIES AND EQUITY Current Liabilities:     Accounts Payable 23.5% 43.2% 17.4%     Accrued Expenses and Other 14.5% 13.9% 7.4%     Unearned Revenue 4.0% 0.0% 0.0%       Total Current Liabilities 42.0% 57.1% 24.8% Long-Term Debt 14.4% 4.9% 53.6% Other Long-Term Liabilities 16.7% 5.9% 0.2% Total Liabilities 73.2% 67.9% 78.6% Stockholders' Equity:     Common Stock 0.0% 0.0% 0.2%     Treasury Stock -1.1% -7.2% 0.0%     Additional Paid-in Capital 16.5% 49.6% 46.2%     Other -0.6% -1.5% 0.0%     Retained Earnings (Accum. Deficit) 12.1% -8.8% -25.0%         Total Stockholders' Equity 26.8% 32.1% 21.4% Total Liabilities and Equity 100.0% 100.0% 100.0%