Search "[your country] inflation rate [year]" or check your country's statistics office / central bank for the official consumer price index (CPI) change over your specific time period.
If prices rose faster than your salary did, the same paycheck buys fewer goods and services than before — your nominal number went up, but what it can actually purchase went down.
Either can be useful. The official rate reflects a broad basket of goods; your personal spending pattern (e.g. heavy on rent, or heavy on groceries) might have experienced different price changes. Use whichever is more relevant to what you're trying to understand.