The growth of the amount of money in the economy is just one factor that can affect inflation. Other factors include:
changes in a nations productivity
changes in the exchange rate with other countries
changes in the velocity of money
changes in what fraction of financial exchanges are counted in inflation incidences
Given all these additional factors, its no surprise to find that in the short term the money supply does not correlate brilliantly with inflation... but in the long term the correlation is definitely there - i.e. if the money supply grows by a factor of ten over many years, then prices would probably grow by a similar factor. Milton Friedman won his Nobel prize for his work highlighting the long term correlation.