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         1784        653 
1995         3321       1155 
1996         3559       1250 
1997         2306        787 
1998        23157       9768 
1999        14473       5549 
2000        40118      16637 
2001        40952      15960 
2002        32077      14349 
2003        60208      24994 
2004        47510      18224 
2005        83623      25725 
2006       108041      34596 
2007       198727      61149 
2008       120105      34250 
2009        98536      27727 
2010       113742      31662 
2011       168639      46691 
2012       158512      43879 
2013       237123      67433 
2014       580268     149035 
2015       701782     186103 
2016       677076     175714 
2017       576023     155724 
2018       374841     105157 
2019       901180     220397 
2020       651275     166169 
2021       869840     207378 
2022       644712     184582 
2023       592267     169462 
2024       418805     121970