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         1555        571 
1994         2317        836 
1995         3368       1171 
1996         3576       1256 
1997         2326        793 
1998        23250       9803 
1999        14520       5567 
2000        40442      16781 
2001        43005      16675 
2002        32462      14510 
2003        61119      25341 
2004        47908      18374 
2005        85203      26198 
2006       110649      35359 
2007       203640      62466 
2008       124826      35534 
2009       101482      28523 
2010       118015      32783 
2011       176845      48907 
2012       164244      45416 
2013       254646      72027 
2014       604663     154822 
2015       730131     193620 
2016       714762     184631 
2017       601151     162181 
2018       395896     110931 
2019       929199     228126 
2020       684479     175355 
2021       893299     213817 
2022       663291     189713 
2023       602253     173402 
2024       243323      70437