<P> According to the Pew Research Center the percentage of Protestants in the United States has decreased from over two - thirds in 1948 to less than half by 2012 with 48% of Americans identifying as Protestant . </P> <P> The data here comes from Gallup, which has polled Americans annually about their denominational preferences since 1948 . Gallup did not ask whether a person was a formal member of the denomination . Blank means that there is no data available for a given year . All of the percentages here are rounded, so 0% could actually mean 0.01% to 0.49% . </P> <Table>% of Americans by religious affiliation (1948--2017) <Tr> <Th> Religion </Th> <Th> 1948 </Th> <Th> 1950 </Th> <Th> 1955 </Th> <Th> 1960 </Th> <Th> 1965 </Th> <Th> 1970 </Th> <Th> </Th> <Th> 1980 </Th> <Th> 1985 </Th> <Th> </Th> <Th> 1995 </Th> <Th> 2000 </Th> <Th> 2005 </Th> <Th> </Th> <Th> 2015 </Th> <Th> 2017 </Th> </Tr> <Tr> <Td> Protestant </Td> <Td> 69% </Td> <Td> 66% </Td> <Td> 70% </Td> <Td> 67% </Td> <Td> 69% </Td> <Td> 65% </Td> <Td> 60% </Td> <Td> 61% </Td> <Td> 57% </Td> <Td> 56% </Td> <Td> 56% </Td> <Td> 52% </Td> <Td> 49% </Td> <Td> 45% </Td> <Td> 38% </Td> <Td> 38% </Td> </Tr> <Tr> <Td> Catholic </Td> <Td> 22% </Td> <Td> 25% </Td> <Td> 22% </Td> <Td> 25% </Td> <Td> 24% </Td> <Td> 26% </Td> <Td> 27% </Td> <Td> 28% </Td> <Td> 28% </Td> <Td> 25% </Td> <Td> 27% </Td> <Td> 25% </Td> <Td> 23% </Td> <Td> 21% </Td> <Td> 23% </Td> <Td> 21% </Td> </Tr> <Tr> <Td> Non-denominational Christian </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> 5% </Td> <Td> 7% </Td> <Td> 8% </Td> <Td> 9% </Td> <Td> 9% </Td> </Tr> <Tr> <Td> Mormon </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> 2% </Td> <Td> 1% </Td> <Td> 1% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 2% </Td> </Tr> <Tr> <Td> Jewish </Td> <Td> 4% </Td> <Td> 4% </Td> <Td> 4% </Td> <Td> 3% </Td> <Td> 3% </Td> <Td> 3% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 2% </Td> </Tr> <Tr> <Td> Other religions </Td> <Td> 0% </Td> <Td> 3% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 4% </Td> <Td> 2% </Td> <Td> 3% </Td> <Td> 5% </Td> <Td> 5% </Td> <Td> 5% </Td> <Td> 5% </Td> <Td> 4% </Td> <Td> 6% </Td> <Td> 5% </Td> </Tr> <Tr> <Td> None </Td> <Td> 2% </Td> <Td> </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 3% </Td> <Td> 6% </Td> <Td> 7% </Td> <Td> 8% </Td> <Td> 9% </Td> <Td> 6% </Td> <Td> 8% </Td> <Td> 10% </Td> <Td> 14% </Td> <Td> 17% </Td> <Td> 20% </Td> </Tr> <Tr> <Td> Undesignated </Td> <Td> 3% </Td> <Td> 2% </Td> <Td> 1% </Td> <Td> 1% </Td> <Td> 0% </Td> <Td> 0% </Td> <Td> 1% </Td> <Td> 0% </Td> <Td> 1% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 2% </Td> <Td> 4% </Td> <Td> 4% </Td> <Td> 4% </Td> </Tr> </Table> <Tr> <Th> Religion </Th> <Th> 1948 </Th> <Th> 1950 </Th> <Th> 1955 </Th> <Th> 1960 </Th> <Th> 1965 </Th> <Th> 1970 </Th> <Th> </Th> <Th> 1980 </Th> <Th> 1985 </Th> <Th> </Th> <Th> 1995 </Th> <Th> 2000 </Th> <Th> 2005 </Th> <Th> </Th> <Th> 2015 </Th> <Th> 2017 </Th> </Tr>

Are most of the religions in the united states monotheistic