Time sure flies by. From 1979 to 1993 the Mexican Peso ranged from 17 to one dollar to as high as 3200 to the dollar, in 1982 Mexico defaulted on it's foreign loans, so inflation soared and the pesos value sank.
I went to RP for the 1st time in 1983 and kept about $100 in pesos to use the next time, A year later, they were then worth about $60, Wow! There have been periods were the peso would plummet by 10-20% in a week.
In 1993 Mexico got it's financial house in order so a New Peso was issued where they took the last 2 zeros off from the old pesos 3120 to 1, became 3.12 to the dollar.
Life became good again for the people with a stable peso. Along comes 1994 with the PRI party trying to stay in power, So President Salinas has the treasury buy Pesos to keep it stable.
In comes newly elected Pres. Zidello who finds out that the Mexican treasury is almost broke from the previous regimes Peso buying binge. A few weeks later the peso goes to 4-1, the locals were livid.
That is why the dollar is king. That old 12.5 to 1 peso from 1964 is really a 11,200 to 1 Peso. Recounting History is longwinded, Sorry.