From the wikipedia on Religion in the United States:
A late 2009 online Harris poll of 2,303 U.S. adults (18 and older)[59]
found that "82% of adult Americans believe in God", the same number as
in two earlier polls in 2005 and 2007. Another 9% said they did not
believe in God, and 9% said that they were not sure. It further
concluded, "Large majorities also believe in miracles (76%), heaven
(75%), that Jesus is God or the Son of God (73%), in angels (72%), the
survival of the soul after death (71%), and in the resurrection of
Jesus (70%). Less than half (45%) of adults believe in Darwin's theory
of evolution but this is more than the 40% who believe in
creationism..... Many people consider themselves Christians without
necessarily believing in some of the key beliefs of Christianity.
However, this is not true of born-again Christians. In addition to
their religious beliefs, large minorities of adults, including many
Christians, have "pagan" or pre-Christian beliefs such as a belief in
ghosts, astrology, witches and reincarnation.... Because the sample is
based on those who agreed to participate in the Harris Interactive
panel, no estimates of theoretical sampling error can be calculated."
And from the actual poll, which was conducted at the end of 2009.
To = Total
Ca = Catholic
Pr = Protestant
Jw = Jewish
BA = Born-AgainChristian
To Ca Pr Jw BA
% % % % %
God 82 94 92 79 97
=> Miracles <= => 76 81 87 63 95 <=
Heaven 75 86 90 48 97
Jesus is God or the Son of God 73 90 91 6 97
Angels 72 83 88 36 95
Survival of the soul after death 71 82 85 37 91
The resurrection of Jesus Christ 70 87 88 5 97
Hell 61 70 73 21 89
The Virgin birth (Jesus born of Mary) 61 74 79 5 92
The Devil 60 69 77 7 89
Darwin’s theory of evolution 45 51 32 80 16
Ghosts 42 44 33 10 37
Creationism 40 37 56 20 68
UFOs 32 32 26 20 25
Astrology 26 26 20 19 21
Witches 23 22 23 8 27
Reincarnation – that you were once another person 20 19 13 18 14
So, the answer, if America is any representation of the whole, is 81% of Catholic [in America] believe in miracles.
Having not investigated the polling methods, I can't speak with any authority as to whether the numbers are accurate. Now can I say by what criteria the pollsters categorized people as Catholic and believing in miracles. My suspicion is that they were direct questions. And for what it's worth, most folks who I would say used to be Catholic would probably self-identify as Catholic.