The CPI takes a constant basket of goods and sees how the price changes from year to year. If the price of the basket of goods increases, then there is price inflation. If the price of the basket of goods decreases, then there is deflation.
Copper and tin mainly make up bronze but other elements include phosphorus, manganese, silicon and aluminium.
Most bronze is made by smelting copper and tin together. When it's cast for use in statues, it often contains between about 10% tin and a little zinc and lead. When it's used in bells it usually has between 20 and 25% tin. Additives are included when the metal needs to be more workable, harder, or easier to cast.