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          471        179 
1992          746        302 
1993         1308        487 
1994         1684        618 
1995         3096       1080 
1996         2983       1054 
1997         1872        646 
1998        22319       9432 
1999        13586       5213 
2000        38754      16026 
2001        39551      15366 
2002        31183      13942 
2003        58008      24132 
2004        46582      17873 
2005        81850      25192 
2006       105512      33856 
2007       192673      59522 
2008       114068      32623 
2009        94199      26540 
2010       119543      32970 
2011       160157      44406 
2012       151339      41929 
2013       223835      63755 
2014       568967     144947 
2015       802149     210115 
2016       665603     172659 
2017       558117     150908 
2018       355500      99847 
2019       871259     212692 
2020       623869     158813 
2021       842232     200260 
2022       627955     179731 
2023       563459     161144 
2024       628311     180911 
2025       170271      48511