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          444        170 
1992          721        293 
1993         1283        478 
1994         1631        600 
1995         2900       1014 
1996         2895       1024 
1997         1787        619 
1998        21452       9128 
1999        12875       4962 
2000        37998      15694 
2001        39346      15253 
2002        32678      14378 
2003        56311      23474 
2004        45366      17432 
2005        79937      24633 
2006       102904      33094 
2007       187678      58182 
2008       106482      30597 
2009        89376      25239 
2010       141523      38062 
2011       150784      41876 
2012       141812      39344 
2013       215032      61319 
2014       547134     139280 
2015       795287     209289 
2016       645590     167628 
2017       544401     147355 
2018       338698      95235 
2019       851159     207799 
2020       593115     150479 
2021       803496     190130 
2022       608393     174162 
2023       548294     156910 
2024       607567     174358 
2025       561759     161966