I didn't ask how many countries have pegged - I asked how many countries have pegged successfully. To peg a currency, you have to maintain adequate forex reserves. In small countries like Botswana, this is not so hard, especially when you are really basing your economy on dollar based products like diamonds and tourism. In large economies like SA - with multiple trading partners and large services industries, this is a huge ask. Hence my question - most countries (real economies) that have tried have failed miserably (Argentina, Thailand are the classic case studies). There is also the well documented inflationary impact of large currency reserves.