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         1755        643 
1995         3321       1155 
1996         3489       1226 
1997         2300        785 
1998        23151       9765 
1999        13533       5235 
2000        40081      16621 
2001        42117      16344 
2002        32031      14329 
2003        60137      24968 
2004        47476      18212 
2005        83533      25697 
2006       107880      34549 
2007       198309      61037 
2008       119650      34128 
2009        98332      27673 
2010       113396      31571 
2011       168089      46543 
2012       158229      43802 
2013       236021      67132 
2014       579345     148798 
2015       700538     185755 
2016       675744     175417 
2017       576406     155667 
2018       373399     104764 
2019       899336     219902 
2020       650531     165891 
2021       868792     207143 
2022       643955     184368 
2023       586982     168036 
2024       447642     130496