How to display properly Dataset with index column?

Question

I'm trying to construct and display properly DataSet. Everything works fine, except the index column('Year'). I'm trying different variants:

Example 1:

data := Dataset[{<|"Year"-> Range[t],"x1"-> Column[Array[S[#]&,t]]
                ,"x2" -> Column[Array[R[#]&,t]], 
                "x3" -> Column[Array[Y[#]&,t]], 
                "x4"-> Column[Array[S[#]/R[#]&,t]]|>}]
    data

Output:

Example 2:

data := Dataset[{<|"Year"-> Column[Range[t]],"x1"-> Column[Array[S[#]&,t]]
                ,"x2" -> Column[Array[R[#]&,t]], 
                "x3" -> Column[Array[Y[#]&,t]], 
                "x4"-> Column[Array[S[#]/R[#]&,t]]|>}]

In this example, all columns display horizontally.

So, what is the right approach to solve this problem?

Answer 1

t = 10;
keys = {"Year","x1","x2","x3"};
years = Range[t];
x1values = RandomReal[10, t]; (* your Array[S, t] *)
x2values = RandomInteger[1000, t]; (* your Array[R, t] *)
x3values = RandomWord["Noun", t];

data = Dataset[AssociationThread[keys -> #]&/@
    Transpose[{years, x1values, x2values, x3values}]]

ds = Dataset[AssociationThread[{"Year", "x1", "x2", "x3", "x4"} -> #] & /@ 
  Transpose[{Range[10], Array[S, t], Array[R, t], Array[Y, t], Array[S[#]/R[#] &, t]}]]