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          503        190 
1992          936        367 
1993         1663        608 
1994         2323        838 
1995         3371       1172 
1996         3576       1256 
1997         2329        794 
1998        23258       9806 
1999        14524       5569 
2000        40470      16793 
2001        43046      16691 
2002        32478      14518 
2003        61203      25372 
2004        47956      18392 
2005        85335      26238 
2006       110796      35403 
2007       204001      62562 
2008       125128      35615 
2009       101772      28600 
2010       118259      32848 
2011       177394      49059 
2012       164748      45535 
2013       255940      72318 
2014       606907     155159 
2015       730814     193703 
2016       626377     164115 
2017       602932     162426 
2018       396725     111035 
2019       931707     228348 
2020       686044     175768 
2021       894540     214129 
2022       664146     189969 
2023       603263     173703 
2024       220639      63772