Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          503        190 
1992          936        367 
1993         1666        609 
1994         2326        839 
1995         3571       1239 
1996         3576       1256 
1997         2329        794 
1998        23263       9808 
1999        14529       5571 
2000        40478      16797 
2001        43072      16702 
2002        32518      14536 
2003        61279      25404 
2004        48012      18414 
2005        85522      26292 
2006       110953      35451 
2007       204336      62656 
2008       125466      35704 
2009       102078      28684 
2010       118618      32944 
2011       177941      49209 
2012       167012      45864 
2013       258126      72730 
2014       640060     162723 
2015       743067     196546 
2016       571067     152319 
2017       607408     163136 
2018       400456     111728 
2019       940029     230129 
2020       690108     176918 
2021       896994     214766 
2022       665618     190385 
2023       605025     174202 
2024       208990      60255