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          492        186 
1992          770        310 
1993         1356        504 
1994         2266        818 
1995         3362       1169 
1996         3573       1255 
1997         2326        793 
1998        23240       9799 
1999        14511       5564 
2000        40413      16768 
2001        42963      16660 
2002        32426      14494 
2003        61047      25314 
2004        47856      18356 
2005        84922      26113 
2006       110381      35277 
2007       203171      62340 
2008       124445      35427 
2009       100969      28383 
2010       117591      32672 
2011       175967      48667 
2012       163695      45267 
2013       253060      71589 
2014       603029     154402 
2015       727934     193029 
2016       713449     184399 
2017       599649     161841 
2018       394653     110596 
2019       929289     228186 
2020       690345     176511 
2021       891685     213372 
2022       662170     189383 
2023       600086     172786 
2024       259592      75218