|Denomination|1870|1880|1890|1900|1910|1920|1930|1941|1949|2001|2011|
|---|---|---|---|---|---|---|---|---|---|---|---|
|Roman Catholic|72.3%|69.4%|64.7%|60.7%|59.8%|59.1%|60.7%|63.1%|69.8%|45.8%|28.9%|
|Calvinist|4.8%|6.1%|7.4%|8.9%|9.9%|10.9%|12.1%|13.6%|15.5%|12.6%|8.5%|
|Lutheran|5.3%|5.5%|5.6%|5.3%|4.9%|4.8%|5%|5.3%|5.4%|2.6%|1.7%|
|Jewish|16.6%|19.7%|21%|23.6%|23.1%|23.2%|20.3%|15.8%|6.4%|0.5%|0.4%|
|Others|1%|1.3%|1.3%|1.5%|2.2%|2%|1.9%|1.6%|1.4%|3.9%|3.5%|
|Without religion|0%|0%|0%|0%|0%|0%|0%|0%|0%|19.5%|22.9%|
|No answer|0%|0%|0%|0%|0%|0%|0%|0%|0%|15.1%|34.1%|

Question: how many denominations never dropped below 20%?
Answer: 1