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          868        344 
1993         1663        608 
1994         2320        837 
1995         3368       1171 
1996         3576       1256 
1997         2326        793 
1998        23250       9803 
1999        14522       5568 
2000        40452      16785 
2001        43018      16681 
2002        32466      14512 
2003        61169      25360 
2004        47941      18387 
2005        85251      26212 
2006       110738      35384 
2007       203785      62505 
2008       125010      35583 
2009       101650      28569 
2010       118154      32820 
2011       177136      48987 
2012       164450      45471 
2013       255182      72177 
2014       605119     154942 
2015       730627     193757 
2016       702255     181464 
2017       601123     162168 
2018       395640     110847 
2019       930302     228111 
2020       685163     175546 
2021       893811     213954 
2022       663720     189836 
2023       602774     173550 
2024       245122      70968