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         1651        604 
1994         2317        836 
1995         3368       1171 
1996         3576       1256 
1997         2326        793 
1998        23250       9803 
1999        14520       5567 
2000        40444      16782 
2001        43012      16678 
2002        32462      14510 
2003        61140      25349 
2004        47919      18378 
2005        85227      26205 
2006       110676      35367 
2007       203692      62480 
2008       124870      35546 
2009       101517      28532 
2010       118044      32791 
2011       176912      48926 
2012       164316      45435 
2013       254737      72054 
2014       604813     154862 
2015       730333     193672 
2016       709226     183225 
2017       600753     162070 
2018       395914     110938 
2019       928116     227745 
2020       684682     175411 
2021       893383     213841 
2022       663430     189755 
2023       602425     173449 
2024       243902      70628