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          532        200 
1992          936        367 
1993         1669        610 
1994         2333        842 
1995         4427       1528 
1996         3602       1265 
1997         2340        798 
1998        23334       9837 
1999        14618       5609 
2000        40729      16914 
2001        41798      16305 
2002        32949      14716 
2003        61998      25697 
2004        48683      18680 
2005        87034      26731 
2006       112732      35973 
2007       207761      63592 
2008       128694      36570 
2009       104605      29370 
2010       121586      33725 
2011       183191      50644 
2012       169844      46984 
2013       264953      75132 
2014       660963     168530 
2015       773182     204853 
2016       577673     154226 
2017       587589     157683 
2018       406722     114100 
2019       927573     226446 
2020       712806     182962 
2021       925127     222518 
2022       692456     197972 
2023       628787     180944 
2024        95769      27970